For the first time, Republican presidential candidate Donald Trump has neared the 50 percent mark in a national poll – this one by CNN:

[T]he new survey finds Trump's lead is dominant, and his support tops that of his four remaining opponents combined. The businessman tops his nearest competitor by more than 30 points: 49% back Trump, 16% Marco Rubio, 15% Ted Cruz, 10% Ben Carson and 6% John Kasich.

Over the weekend, a new NBC News/Wall Street Journal/Marist poll showed both Ted Cruz of Texas and Marco Rubio of Florida clearing the 20 percent hurdle that would allow them to collect at least a handful of delegates here:

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But it is that national CNN poll that has people talking. From an email sent to The Atlanta Journal-Constitution on Monday from Alan Abramowitz, the Emory University political scientist:

"[Trump is] at 49% in new CNN national poll and has to be considered the prohibitive favorite to win the nomination. But 35 percent of Republicans say they definitely could not support him in general election. Clinton has 17 point lead in Dem race versus Sanders and 20 percent of Democrats say they definitely could not support her in general election.

"I strongly suspect that both the 35 percent and the 20 percent are gross exaggerations of what would actually happen in a general election match-up, since they're not based on real, head-to-head choices versus the opposing party nominees.

"But it is significant that Trump's number is substantially higher than Clinton's. And the rhetoric on the GOP side supports the argument that unity is going to be much harder to achieve for them. And this was before the latest KKK/David Duke/white supremacist controversy for Trump. Trump is a ticking time bomb for the GOP."